How to Outsmart Your Peers on Steel Pipes



It has long been known that the properties of some metals could be altered by heat treating. Grains in metals tend to grow larger as the metal is heated. A grain can grow larger by atoms moving from another grain that may ultimately disappear. Dislocations can not cross grain boundaries quickly, so the size of grains determines how quickly the dislocations can move. As expected, metals with small grains are more powerful but they are less ductile. Figure 5 reveals an example of the grain structure of metals. Quenching and Solidifying: There are numerous ways in which metals can be heat dealt with. Annealing is a softening process in which metals are heated and after that allowed to cool gradually. A lot of steels may be solidified by heating and quenching (cooling rapidly). This procedure was used rather early in the history of processing steel. In fact, it was believed that biological fluids made the very best quenching liquids and urine was in some cases used. In some ancient civilizations, the red hot sword blades were often plunged into the bodies of hapless prisoners! Today metals are satiated in water or oil. Actually, satiating in salt water options is quicker, so the ancients were not entirely wrong.Quenching lead to a metal that is very difficult but likewise brittle. Carefully heating a solidified metal and allowing it to cool gradually will produce a metal that is still difficult however also less breakable. This process is called tempering. (See Processing Metals Activity). It results in lots of small Fe3C speeds up in the steel, which block dislocation movement which thus provide the strengthening.Cold Working: Since plastic deformation arises from the motion of dislocations, metals can be enhanced by avoiding this motion. When a metal is bent or shaped, dislocations are created and move. As the number of dislocations in the crystal increases, they will get twisted or pinned and will not be able to move. This will reinforce the metal, making it harder to warp. This process is called cold working. At higher temperature levels the dislocations can rearrange, so little reinforcing occurs.You can try this with a paper clip. Unbend the paper welded steel pipe clip and flex one of the straight areas backward and forward several times. Envision what is occurring on the atomic level. Notification that it is more difficult to flex the metal at the same place. Dislocations have actually formed and become twisted, increasing the strength. The paper clip will eventually break at the bend. Cold working clearly only works to a specific extent! Excessive contortion results in a tangle of dislocations that are not able to move, so the metal breaks instead.Heating removes the results of cold-working. When cold worked metals are heated, recrystallization happens. New grains form and grow to take in the cold worked portion. The brand-new grains have fewer dislocations and the initial properties are brought back.

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